DESCRIPTION (Applicant's Description): The purpose of this postdoctoral research program is to train a select group of young physicians and scientists in the fundamentals of basic research in immunology and tumor biology including immunological mechanisms and the use of immunological techniques to detect, diagnose and treat cancer. The goal is to produce outstanding independent investigators capable of answering fundamental questions in these areas. Trainees will be selected from superior residents in their pathology program who have completed 2-3 years of post-doctoral training and from superior candidates with an M.D. and/or Ph.D. degree from outside this program. Criteria for selection are a commitment on the part of the potential trainees to a career in research and teaching and our estimate that the candidate has outstanding potential for success in such a career. Continued support for 5 trainee/year is requested, distributed approximately evenly among the 1st, 2nd and 3rd year of training. Training will require 2-3 years. This program is modeled on the highly successful Research Associate program at NIH in which research training is primarily accomplished by intense daily exposure of trainees to one or a small group of outstanding preceptors who are themselves bench scientists and who are committed to teaching. Such training will be supplemented by extensive reading of the literature, departmental and interdepartmental seminars, formal course work, and participation in national scientific meetings. Trainees will be exposed to a wide variety of immunological, cellular and molecular biological strategies to study neoplasia and immune response. This broad exposure will make trainees aware of both the advantages and limitations of different methodologies, will render them capable of informed interpreta-tion of data derived from various disciplines, and will enable them to select appropriate experimental approaches for tackling research problems they may encounter in subsequent years. Trainees will acquire in depth experience in a smaller number of these approaches, depending on the specific research interests of the individual and the preceptor. Following completion of the program, trainees will be prepared to engage in an independent career in cancer research, immunopathology or basic immunology.